NppFTP upload works only for blank or very small filesbrowsing

Hi,
I am using Notepad++ with NppFTP on a Windows 10 PC with Windows and Norton firewalls turned off, and I’m trying to upload .css and .php files using SFTP to my child theme in my Wordpress site hosted by Godaddy. I can create new folders and download any file, but when it comes to uploading It works only if the files are blank or less than appr. 30 lines of code…Here’s the NppFTP output…Note that the only difference in the 2 upload attempts is the file size. Also note I have the same problem with Filezilla, and I tried it with FTP port 21 instead of SFTP port 22- no luck: